Teemo is rework-ready.

I am a Teemo main. I've been playing him since I can remember (on 2 or 3 accounts), and one thing has stuck out. He's become under-powered mid to late game and hasn't had a real rework since v5.16

Here are the problems I've found:

Q as it stands is basically the only damaging ability he has mid and late game. Sure, he picks up a few kills or assists because of people on 20 hp walking into shrooms, but that's about it. Late game, it acts as your ult because of it's damage potential with full ap. Blinds for some reason. The blind is extremely insignificant, based on everything I've seen. Lastly, it doesn't apply poison damage, even though it's a dart.

W is not an escape. A champion this squishy needs an escape. Even Ezreal has an escape, and he's not even a scout. It doesn't break you free from slows or do much of anything except give a slight speed boost.

E does not scale well and the poison damage early-mid and late game is almost to completely unnoticeable.

R as it stands does very little damage late game, even with full ap. Slows for some reason.

I've often thought, "Why does a giant dart blind people when it smacks into them, and why does a mushroom that explodes into a cloud slow people?" I believe it could be fixed with some tweaks and reworking his abilities to be more poison based and thus making him a more ap reliant champ.

Q could deal double or 1.5% poison damage on hit from his E and then slow the target, since it is a larger dart hurdling towards your enemy. Get rid of "on hit damage". It's dart, not a knife.

W could do something like turn him invisible for like 2 seconds and give a boost of movement speed so he has a better chance of getting out alive other than the small percent he already has. Maybe it could even leave behind a decoy shroom that fears all enemies for 0.25 seconds?

E could do much more poison damage over time the higher the ability level ["20/30/50/80/111" instead of the "6/12/18/24/30 (+10% AP)" it currently does]. It could also scale with "50%" of his ap instead of "30%" on hit. Get rid of "on hit damage". It's poison, not a bomb. It could also apply whatever magic penetration you have, but double it. Maybe.

R could blind people, seeing as it does explode into a cloud. It could also scale with "40% AP" instead of the current "12.5% AP".

Besides these changes, everything else is basically fine. With these changes, I think he would certainly become more fun to play, he wouldn't be as both underwhelming and underpowered as he feels and looks like when played, and may even be viable in LCS.

He would also become much more unique, since he would be the only champion whose abilities are almost completely poison based which fits perfectly with his lore.